Antenatal Betamethasone and Fetal Growth in Prematurely Born Children: Implications for Temperament Traits at the Age of 2 Years

OBJECTIVE. We explored whether repeated dose of antenatal betamethasone and variation in intrauterine growth of prematurely born children predict temperament characteristics at the age of 2 years. PATIENTS AND METHODS. The patients (n = 142) were prematurely born children (mean gestational age: 31.0 weeks; range: 24.6-35.0 weeks) who participated in a randomized and blinded trial testing the effects of a repeated dose of antenatal betamethasone in imminent preterm birth. Fetal growth was estimated as weight, length, and head circumference in SDs according to Finnish growth charts. Parents assessed their toddlers' temperament with 201 items of the Early Childhood Temperament Questionnaire (mean child corrected age: 2.1 years). RESULTS. No significant main effects of repeated betamethasone on toddler temperament existed. However, a significant interaction between study group and duration of exposure to betamethasone emerged; those exposed to a repeated dose for >24 hours before delivery were more impulsive. One-SD increases in weight, length, and head circumference at birth were associated with 0.14- to 0.19-SD lower levels of negative affectivity (fearfulness, anger proneness, and sadness); 1-SD increases in length, weight, and head circumference at birth were associated with 0.14- to 0.18-SD higher levels of effortful control (self-regulation). CONCLUSIONS. Repeated antenatal betamethasone did not induce alterations in toddler temperament. The results, however, suggest that a longer duration of exposure is associated with higher impulsivity scores. Regardless of betamethasone exposure, slower fetal growth exerted influences on temperament. Our findings indicate prenatal programming of psychological development and imply that more attention is needed to support the development of infants born at the lower end of the fetal growth distribution. Pediatrics 2009;123:e31-e37